Method of manufacturing shoes



May 3, 1966 1 G. HOLE 3,248,748

METHOD OF MANUFACTURING SHOES Filed April 27, 1962 106 106 ,OI 10e EL* 100J 1107 `L100 /1 pl' j 1 i g E 117 I I 'g 113 111 111 f5 Il,

/NI/E/VTOR 'm@ /wfc BY M (JM/l M @uw United States Patent O 3,248,748 METHOD F MANUFACTURING SHOES Lionel G. Hole, Woods Batch, Street, Somerset, England, assignor to C. & J. Clark Limited, Somerset, England, a company of Great Britain Filed Apr. 27, 1962, Ser. No. 190,585 Claims priority, application Great Britain, May 1, 1961, 15,758/61; May 16, 1961, 17,771/61; Aug. 3, 1961, 28,208/61; Nov. 28, 1961, 42,449/61; Dec. -7, 1961,

10 Claims. (Cl. 12-142) This invention relates to the treatment of materials used in the manufacture of footwear and to methods of making footwear, and has particular reference to the conditioning and the forming or shaping of footwear components. l

The main object of the invention is to provide improved methods of and apparatus for modifying the plastic and elastic properties of footwear materials and components,

-such as leather soles and leather, fabric and synthetic lows, therefore, that within a limited temperature range the combined effects of increasing the moisture content and the temperature of leather leads to an increase in its area.

It has been found that these effects can be used to bringv about varying degrees of stress relaxation in lasted uppers, and, moreover, it is well known that in shoe manufacture the conforming of the upper to a last of complex asymmetrical shape applies strains to the upper material. It has been customary practice to partially relax the resulting stresses in the upper material by leaving the upper on the last for an appreciable length of time, that is, from 3 to 7 days. More recently the use of dry heat has been employed to set the upper .to shape in much shorter time, for instance, from 5 to l0 minutes, and this has materially affected shoemaking techniques.

We have found by combining the heat setting technique with a preceding stress-relaxing stage that not only is a substantially better set obtained, but in addition the stability of the set is much improved. Further, these improvements in shoe shape and shape stability can be achieved in even shorter periods of time, that is, from 2 to 3 minutes. This is important in several respects; for example, the storage aspects of the stress relaxing/heat setting machine are reduced, since the number of shoes being treated correspond to only 2 to 3 minutes produc` tion. This has considerable advantages during the starting-up and the closing down of a production line, especially if this occurs because of relatively short breaks in production. Other advantages are obtained which are associated with the actual planning of the input.

It would be usual for the two stages of stress relaxation and heat setting to be performed consecutively without any substantial delay. For some purposes, however, only one or other of these stages may be applied to the shoe.

According to that aspect of this invention which concerns the provision of improved methods for the manufacture of shoes, the invention may be considered broadly as characterised in that stress relaxation conditioning of the upper is effected after lasting.

A shoe made by a method in which stress relaxation of the upper is effected may use an upper which has been subjected to pre-lasting conditioning. That is, the essential steps of shoe manufacture would then comprise preconditioning to modify the physical properties of the shoe upper material preparatory to lasting, the performing of conventional lasting operations on the pre-conditioned upper, effecting stress relaxation conditioning of the upper after lasting, and finally, heat setting of the reconditioned upper. In most instances, sole laying would follow the stress relaxation of the upper.

As applied, for example, to the making of a cemented sole shoe, which includes the step of prelasting conditioning (preferably a rapid conditioning) of the shoe upper, the invention may be viewed as comprising the steps of lasting the conditioned upper (including the joining of an insole to the upper), reconditioning the upper (again preferably rapidly) to facilitate stress relaxation therein, applying adhesive to the prepared bottom of the upper assembly (before or after stress relaxation conditioning) and heat setting the upper and heat drying and activating the adhesive prior to sole attachment.

More particularly, the unattached shoe upper, after a first or initial rapid prelasting conditioning, is attached to a last (or to an insole carried thereby) and the upper is lasted, preferably in, or immediately after removal from, conditions of controlled humidity and elevated temperature. After lasting the upper assembly is reconditioned to facilitate stress relaxation in the upper and adhesive is applied to the 4prepared bottom of the upper assembly immediately after the stress-relaxing reconditioning, heat being then applied for simultaneously drying and setting the upper and drying and activating the adhesive prior to attachment of the sole. It is usually preferable to apply the adhesive before stress relaxation conditioning. An optional cooling stage may be employed after sole laying so that the shoe when cold may be slipped from the last.

Stress relaxation of the upper after lasting ensures faithful reproduction of the last shape in the shoe after slipping, by removing stresses introduced during lasting. This relaxation process is carried out by a further conditioning operation immediately prior to setting of the upper. A variety of simple `conditioning techniques may be used, either cold or accompanied by varying degrees of heating. The water used for this operation may be applied either from )the liquid or vapour phase.l The ,choice of conditions depends upon the speed and degree of relaxation'required for any particular upper material. The relaxation stage of reconditioning would normally be followed by a heat setting process, although in some circumstances this may not be necessary.

In general, after stress relaxation there is a stage which may be considered briefly as heat setting of the upper. The purpose of this stage, which is carried out at elevated temperatures, is to remove such a proportion of the moisture present and still remaining in the upper from the first and third stages, that it is set into the shape given to it by the last. Underthese conditions the relaxed state of the material induced by the third stage is stabilised, and this being so, the stresses in the upper at slipping will be at a minimum, and hence the retention of last shape by the upper will be at a maximum.

Finally there is the stage which consists in heat activation of sole-attaching adhesive. In many shoe constructions the sole is attached either permanently or temporarily by means of a suitable adhesive, and very often these adhesives are solvent based, so that it is necessary to remove this solvent rapidly before the adhesive can be activated into a suitable condition for bonding. A suitable device using infra-red heating can be used to carry out this stage and the fourth stage concurrently. It is not essential, however, to use infra-red heating, and other techniques may be employed, such as hot air streams or di-electric heating, as referred to again later, or conduction heating.

An important advantage of this invention lies in the substantially increased speed at which stress relaxation and heat setting stages can be carried out. This has been done to the extent that the stress relaxation can be cornpleted within 60 seconds or less and the heat setting stage can be campleted within say minutes. Heating can be effected by infra-red radiation, hot air, or high-frequency electric heating (for example, dielectric heating), o-r by use of a iluidized bed. l According to the form of heating used the heating time will vary and may be reduced to a matter of a few second-s. As already intimated the adhesive activating stage can usually be performed concurrently with the heat set-ting stage by using the same machine.

A rapid cooling stage using cold air streams o-f up to 1,500 feet per minute may be used prior to slipping.

By way of example, the manufacture of two kinds of shoes `by methods provided by this invention will now be described.

The first example is that of making an unlined, stuck sole Ishoe-uppers of full chrome side leather. 1n this case an upper is placed in a prelasting conditioning apparatus which apparatus may comprise a hot plate (together with or forming a moisture source) and a cold plate between which the upper leather blank is disposed. With a hot plate temperature of 90 to 95 C. and a cold plate chilled by suitable means to l0 to 25 C., the upper is allowed to dwell in the apparatus for seconds, and at the end of this period the conditioned upper is released and the operator immediately attaches the upper to a last or to an insole. lThe upper and last assembly is promptly passed -to the next stage of lasting and the upper is lasted while still Warlm if possible; while it is desirable that the upper be warm at lasting, it is not essential. After a number of appropriate making operations have been performe-d, including adhesive application, the upper portion only of the shoe is conditioned for stress relaxation has hereinbefore defined. This can be done by applying a thin film of water (which may contain certain chemical additives), making use of 'any convenient method. The bottom of the unsoled shoe, or upper assembly (which has ,been coated with adhesive) is now immediately placed in a suitable heat setting apparatus; the dwell time in this apparat-us is about 41/2 minutes. Upon removal from the heat setting apparatus the sole is attached by any suitable means. The shoe is now dry, heat-set and ready for slipping from the last. The Ioverall time for this complete process from conditioning to final slipping of the last is l0 to 20 minutes approximately.

The second example is that of a fully lined shoe, made with full chrome tanned calf upper leather and vegetable tanned lining leather. In this case the tempearture gradient conditioner, again sited conveniently to the lasting machines, operates with both plates ho-t (at a temperature of 70 to 75 C.). The upper is placed in the temperature gradient conditioner, and after a dwell of 30 seconds is automatically released, the conditioned upper being promptly attached Ito an insole which is itself attached to a last;'the next upper required for use is immediately placed in the temperature gradient conditioner. The conditioned upper is completely lasted without delay and preferably while still Warm. After the appropriate making operations, just after adhesive application, the operation of stress relaxing conditioning is carried out, by placing the upper in a mist of warm nely divided water droplets for about one minute. The tre-ated shoe is immediately placed in the drying .and heat setting unit. With certain bonding techniques it may be desirable to protect the bottom of the shoe from moisture.

Reference has already been made to various heating techniques, to which further attention will now he given.

in a unit through which the shoe is passed within a period A of say 41/2 minutes. This dries the moisture out of the upper and simultaneously heat-sets the lasted shape into the leather upper. Concurrently the sole adhesive is dried and activated and upon issuing from the unit `the sole and shoe are combined and the bond consolidated by suitable means, e.g., a sole laying press. The appropriate sole may also pass through the unit with the shoe so as to be dried and if the sole has adhesive thereon this adhesive becomes activated. The shoe is now dry, heat-set and sole laid ready for slipping and finishing. lf required the warm shoe can be cooled in a cooling unit for 10 minutes;

for example, air at a suitable temperature may be passed over the shoe at speeds up to 1,500 feet per minute.

Another form of heating apparatus or setting unit is one using a di-electric field. For instance, the reconditioned shoe, with freshly applied adhesive lon the shoe bottom,'is adapted to be placed in the dielectric heat setting apparatus, which consists of a short tunnel with an air stream passing through it at about 1,000 feet per minute. Suitably shaped electrodes energised by a suitable RF. generator are so placed that the shoe is positioned in the eld which the electrodes create. The heating time is from 10-30 seconds at an output from 1-5 kilowatts, and after `the required operation the generator cuts out automatically, -but the shoe remains for about another 15 seconds in the cold air stream. The shoe is then removed, combined with the sole and the bond consolidated in a sole laying press; the shoe may then be slipped after a brief cooling operation.

The accompanying diagrammatic drawings illustrate apparatus suitable for carrying into practice the invention according to several of the various aspects thereof already described.

In tie drawings:

FIG. 1 is a diagrammatic layout of a shoe making installation which embodies various features according to this invention,

FIG. 2 is a developed side elevation of part of the apparatus used in said installation, and

FG. 3 is a cross section on line XX--XX of FG. 2.

In the continuous production shoe making installation diagrammatically shown in FIGS. 1 to 3, the required machinery and apparatus for shoe making is ranged alongside of a closed-loop endless conveyor track 100, part of which may be enclosed in tunnel units. Grouped shoe components are loaded at station 101 onto the track 100, alongside of paired (right land left foot) lasts, carried over said track, all or some of Said group of components, but at least the closed uppers, being first removed for passage through the temperature gradient conditioner 102; dwell time herein may be about 9 seconds. After this initial or preconditioning stage, one or more stitfeners are inserted at station 103, before pulling-over of the preconditioned upper is effected at station 104; two pulling-over machines, one on each side of track are conveniently employed. Toe lasting is then performed at station 105, followed by waist lasting and seat lasting at stations 106, 107 respectively (again using two machines at each station if necessary) with a shank fitting operation performed at the intermediate station 108.

The operations following stiffener insertion (station 103) up to seat lasting (station 107) are performed while the uppers retain the added pliability due to preconditioning land while still at an elevated temperature, these conditions being maintained during interstage periods by traversing the lasts and components through a humidifying tunnel 109 to which access may tbe had at the various stations through apertures or doors in the tunnels; the use of this tunnel, however, is optional.

After seat lasting the shoe bottoms may be dried at station 110 (preferably by infra-red radiation) and then pounding and roughing is effected at station 111. Assuming an adhesive is employed for sole attachment, this is applied at station 112.

The lasted uppers next enter another humidifying tunnel 113 wherein stress relaxation conditioning is effected, and then pass through a heat setting tunnel 114. The length of tunnel 114 depends mainly on the form of heating required; for instance, if dielectric heating is used only a short tunnel is required.

On emerging from the heat setting tunnel 114 the operation of sole laying is performed at station 115, followed, if required, by cooling in a further tunnel 116, the final operation usually being heel attachment at' station 117, whereafter the shoe is slipped from the last and after unloading of the shoes at station 118 the empty lasts continue their circulatory movements around the endless track 100.

Stress relaxation conditioning is essentially done 'by exposing the shoe to a fine warm or hot water mist of vapor i.e. small droplets or Vapor, in tunnel 113, so that the upper is rapidly coated with a thin film of moisture. The operating temperature in the mist can be from ambient to 90 C., or, in certain circumstances, using the vapour phase to 120 C., although it has `been found that a mist temperature in the range 30 to 40 C. is very satisfactory. The dwell time in the mist can 4be in the range 1/2 to 5 minutes (usually 1/2 to 1 minute is'adequate); under these conditions stresses are rapidly relaxed and the upper emerges almost strain free.

The use of penetrating agents in the mist at low concentration for instance, 0.1% to 2%, is a considerable aid and such a mist is usually used. Non-ionic or weakly ionic materials are of particular interest, such as the dioctyl ester of sodium sulphosuccinic acid, condens-ation products of di-octyl phenol and ethylene oxide, or nonylphenol tridecyl alcohol and ethylene oxide. Materials of a more strongly ionic character may also be used howeveh, such as methyl dodecyl benzyl trimethyl ammonium chloride and methyl dodecyl xylylene bis-trimethyl am monium chloride.

Heat setting is carried out in tunnel 114 as the result of which the outside surface of the lasted upper is heated to 100-460 C. within 10 to 30 seconds by radiant heaters 119 (see FIG. 3) in the first section A of the tunnel and then the upper passes into the second section B of the tunnel, which is unheated, for about 60 seconds. Finally the lasted upper passes out through another heating stage in the third tunnel section C wherein the outside leather temperature is raised to 80-150" C. in 10 to 20 seconds.

During this second heating stage excess moisture is re- Vmoved from the shoe upper and the relaxed shape is stabilized. The setting reaction is particularly effective if a high moisture content has been attained in the stress relaxation stage. Cold air is passed through the whole tunnel 114 at speeds from 300-1000 fpm.

Other heating setting techniques after stress relaxation can -be used in tunnel 114, such as a uidised bed (30 seconds at 100 to 150 C.), hot air (5 to 10 minutes at 100 to 150 C.) or diel-ectric heating (10 to 60 seconds).

Prior to this novel combined stress relaxing-heat setting technique the shoe :bottom may have been roughed, and adhesive applied. Deposition of aqueous mists on wet cement, in cases where a soling adhesive is applied, has not been found to be a disadvantage. The heat set ting stage dries and activates this cement and the shoe is ready for sole laying at station 115 immediately it 4leaves the heat setting tunnel 114.

I claim:

1. A method of manufacturing shoes, comprising lasting the shoe upper, and subsequent to completion of lasting and while the upper is still on the last and under tension, conditioning the shoe upper to effect stress relaxation by adding moisture in the form of-a mist of water vapor to the upper, and thereafter heat setting the upper at an elevated temperature Within a period of at most about 10 minutes, whereby the set of the upper is substantially improved and the stability of the set is improved.

2. A method as claimed in claim 1 in which the step of adding moisture to the upper is carried out at temperatures from ambient temperature to 120 C.

3. A method as claimed lin claim 1 further comprising the step of attaching a sole to the upper after the step of stress relaxation.

4. A method as claimed in claim 3 and further cornprising the step of cooling the shoe after the attachment of the sole so that the shoe when cold may be slipped from the last.

5. A method as claimed in claim 1 in which the step of adding moisture to the upper is carried out at a mist vtemperature of up to C.

6. A method as claimed in claim 1 in which a penetrating agent is added to the moisture.

7. A method as claimed in claim 1 in which the moisture is applied to the upper for a period ofl from 30 A seconds to 5 minutes.

8. A method as claimed in claim 1 in which the step of heat setting the upper comprises raising the surface temperature of the upper to a temperature of from to C.

9. A method as claimed in claim 8 in which the heat setting step further comprises allowing the upper to cool for about 60 seconds after the surface temperature has been raised to the initial heat setting temperature, and after the cooling, raising the surface temperature of the upper to a temperature of from 80 to 150 C.

10. A method as claimed in claim 1 which further comprises the step of applying a heat activated sole securing adhesive to the upper immediately before the stress relaxation conditioning, and applying a sole to the upper after the heat setting step, the heat setting step activating the adhesive.

References Cited by the Examiner UNITED STATES PATENTS 1,007,137 10/ 1911 Palmer 38--14 1,594,688 8/1926 Perry 12-1 1,649,337 11/ 1927 Brewer 38-14 1,678,139 7/1928 Furber 12-59.7 1,818,691 8/1931 Carlson 12-59.7 2,206,275 7/ 1940 Woodberry 12-142 2,198,691 4/ 1940 Willmott 12-41.2 2,940,094 6/ 1960 Bromield 12-1 2,793,530 3/ 1961 Bromeld 12-145 X 3,029,535 4/ 1962 Clearman et al. 3914 FRANK .T COHEN, Primary Examiner.

' EDWARD V. BENHAM, JORDAN FRANKLIN,

Examiners. P. D. LAWSON, Assistant Examiner. 

1. A METHOD OF MANUFACTURING SHOES, COMPRISING LASTING THE SHOE UPPER, AND SUBSEQUENT TO COMPLETION OF LASTING AND WHILE THE UPPER IS STILL ON THE LAST AND UNDER TENSION, CONDITIONING THE SHOE UPPER TO EFFECT STRESS RELAXATION BY ADDING MOISTURE IN THE FORM OF A MIST OF WATER VAPOR TO THE UPPER, AND THEREAFTER HEAT SETTING THE UPPER AT AN ELEVATED TEMPERATURE WITHIN A PERIOD OF AT MOST ABOUT 10 MINUTES, WHEREBY THE SET OF THE UPPER IS SUBSTANTIALLY IMPROVED AND THE STABILITY OF THE SET IS IMPROVED. 